Cucurbit Downy Mildew is Spreading in Ohio Despite Hot Weather

Micrograph of a tape mount of spores and sporangiophores of the cucurbit downy mildew pathogen from cucumber leaves. Photo by Francesca Rotondo.

Downy mildew continues to spread in Ohio cucumbers despite the hot and mostly dry weather.  Frank Becker, OSU Extension Wayne County IPM Program Coordinator, brought cucumber leaves with downy mildew symptoms to to our Vegetable Pathology Lab on July 23 for confirmation.

We do this by placing a piece of scotch tape on the underside of a leaf lesion then transferring to tape to a glass slide and looking for characteristic spores and sporangiophores (branched, threadlike structures that produce the spores) under a microscope. The samples came from commercial cucumber fields in Wooster and Apple Creek in Wayne County, and both were positive for downy mildew.

Although we have confirmed reports in only Medina and Wayne counties, cucurbit downy mildew is likely present in most northern Ohio counties.  The map of downy mildew reports shows confirmed cases in Ontario, Michigan and western New York as well. All of these reports are from cucumbers; this clade, or strain of the pathogen affects cucumbers and cantaloupe, but not squash or pumpkins. We don’t expect downy mildew on squash and pumpkins until the other known clade, which has a broader host range, migrates to the Midwest from the Southeast.

Cucurbit downy mildew as of July 24, 2020. cdm.ipmpipe.org.

 

 

 

 

 

 

 

 

Fungicide recommendations are posted here.  If you suspect downy mildew in any cucurbit, please send us a sample.  This will help us track the disease and provide early warnings to growers to enable timely protection of cucurbit crops. Our diagnostic service is free to commercial growers in Ohio; gardeners may also send cucurbit downy mildew samples to us free of charge.  Instructions for sample submission are posted here.

Downy mildew in cucumber.

 

 

Ready to manage spider mites?

With the current hot and dry weather conditions in Ohio, we expect to hear reports of spider mite outbreaks on specialty crops. Because mites are tiny, they are often overlooked or misdiagnosed as a disease. Infested leaves have fine webbing on the leaf undersides. Tomato leaves damaged by spider mites usually have yellow blotches, while bean leaves show white stipples or pin-prick markings from mite feeding. Pumpkins can tolerate moderate levels of mites, but watermelons are more sensitive to injury from mite feeding. A simple method of diagnosing spider mites is to shake leaves over a piece of paper and look for moving specks that are visible to the naked eye. A closer look with a magnifier can show the tiny mites that are white, marked with two large dark spots on the middle of the body.

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OHIO DEPARTMENT OF AGRICULTURE PARTNERS WITH OSU EXTENSION TO PROVIDE ONLINE PESTICIDE RECERTIFICATION OPPORTUNITIES

The temporary online trainings during the COVID-19 Pandemic allow applicators and fertilizer certificate holders to meet their continuing education requirements.

REYNOLDSBURG, Ohio (June 29, 2020) – During the COVID-19 Pandemic, the Ohio Department of Agriculture (ODA), is partnering with the Ohio State University Extension Pesticide Safety Education Program (PSEP) to temporarily provide online recertification for pesticide applicators and fertilizer certificate holders whose licenses expired in spring of 2020. The online recertification will be available Monday, July 6. For commercial applicators, it will be available August 10. For more information or to register for the online recertification, visit pested.osu.edu/onlinerecert.

The online option allows private applicators and fertilizer certificate holders due for training by March 31, 2020 and commercial applicators due for training by September 30, 2020 to meet their continuing education requirements. The cost for online training is $35 for private applicators and $10 for fertilizer certification. The price per credit hour for commercial applicators is $15. If you don’t know your license number, please call ODA at 614-728-6987, choose option 1.

Applicators are still required to meet their recertification requirements to renew licenses and certifications. As a result of HB 197, applicators have until 90 days after the emergency is over or December 1, whichever comes first, to complete their requirements. Recertification status can be checked online at https://agri.ohio.gov/wps/portal/gov/oda/divisions/plant-health/pesticides/recert-search. Applicators must also submit a completed renewal application and pay an additional fee to the ODA for licensure.

For additional information regarding online recertification, please contact the Ohio Department of Agriculture at 614-728-6987, and press 1 for licensing recertification or the OSU Pesticide Safety Education Program at 614-292-4070.

Commercial applicators must earn at least five recertification credit hours every three years, and private applicators must earn at least three recertification credit hours every three years. One hour (60 minutes) must be earned by taking one or more core education classes, one half-hour (30 minutes) of education in each category on the license, and the remaining time requirement can be met by attending classes in any category.

Another Cucumber Downy Mildew Outbreak in MI – and Closer to Home

Outbreaks of cucumber downy mildew on two commercial farms in Monroe County, MI were detected on June 29. Monroe County is in southeast Michigan and borders Ohio’s Lucas County. In addition, spores of the downy mildew pathogen have been captured in spore traps in four Michigan counties, so downy mildew is ramping up and very likely to be in cucumbers in northern Ohio at this time.

Downy mildew sporulation on underside of a cucumber leaf.

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Spotted Lanternfly Continues to Develop

Author: Amy Stone

Originally posted on the Buckeye Yard and Garden OnLine

Life-Cycle Illustration of SLF

While the spotted lanternfly (Lycorma delicatula) (SLF) has not been detected in Ohio, the Ohio Department of Agriculture (ODA), along with the Ohio State University (OSU) and the Ohio Department of Natural Resources (ODNR) are urging Ohioans to continue to be on the look-out for this invasive insect. Many are using the Great Lakes Early Detection Network (GLEDN) App to report tree-of-heaven (Ailanthus altissima), a favorite food or host for this plant hopper, especially as an adult, and then revisiting the tree looking for signs and symptoms of SLF throughout the year.

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Poison Hemlock is Blooming

 

Originally Posted OSU BEEF Newsletter

– Christine Gelley, Agriculture and Natural Resources Educator, Noble County, OSU Extension

 

Poison hemlock is up and actively growing right this minute. It is already prevalent on roadsides in Noble County. If you stand next to poison hemlock it will feel like you are in that scene from “Alice in Wonderland” where the flowers are giant, and she is tiny. It looks like Queen Anne’s Lace, but much larger. It blooms earlier and it is has distinct purple spots on the stem.

Control with a broadleaf killer like 2,4-D doesn’t eliminate ALL the competition for next generation hemlock plants.

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Early Season Cucurbit Pests

Jim Jasinski, Dept. of Extension, Celeste Welty, Dept. of Entomology

Although it’s been wet over most of the state recently, the temperatures are warming up allowing growers to get into their fields to direct seed or transplant pumpkin, squash, melon and cucumbers through May and into June. By now most decisions about how to manage key early season pests may have already been made with the purchase of systemic seed treatment or plans to treat transplant water using neonicotinoid insecticides. Some growers may have decided to forego systemic treatments and rely on scouting and treatment using foliar insecticides when thresholds are exceeded.

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Poison Hemlock and Wild Parsnip are Blooming in Southern Ohio

 

Originally posted on Buckeye Yard and Garden Online

By Joe Boggs- June 3, 2020

Poison hemlock (Conium maculatum) and wild parsnip (Pastinaca sativa) are two of our nastiest non-native weeds found in Ohio.  Poison hemlock is one of the deadliest plants in North America.  Wild parsnip can produce severe, painful blistering.  Both are commonly found growing together.

Poison hemlock and wild parsnip are members of the carrot family, Apiaceae.  The old name for the family was Umbelliferae which refers to the umbel flowers.  They are a key family feature with short flower stalks rising from a common point like the ribs on an umbrella.

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